A process plant is a complex, multifaceted entity, a structured organization of physical elements, operated for economic and other criteria that are often industry-specific. A process plant has a number of different stakeholders who can affect and/or are affected by its operation. Critical to the operation of many process plants today is a process control system, which ensures that appropriate parameters are measured and actions taken, plant personnel are kept informed, abnormal situations are identified and addressed, and business processes are integrated. Automation, monitoring, and control systems are employed in diverse applications, such as residential, shipping, warehousing, refining and petrochemical plants, the petroleum and natural gas supply chain, pulp and paper manufacturing, electrical power generation, chemical production, food production, wastewater treatment, discrete product manufacturing, cable-laying ships, tunnel ventilation control, and mining operations.
In many automation, monitoring, and control applications the cost of running wires from nodes such as sensors, actuators and user interfaces to an analysis system limits the number and location of such nodes initially deployed. Cost and difficulty of wiring installation may also limit the deployment of additional nodes in an already-functioning system. The recent development of wireless communication technologies, such as Bluetooth, IEEE® 802.11, RFID and others, promises a solution to such wiring costs, but not without introducing new challenges to the reliability and security of automation, monitoring, and control systems.
Some devices (or nodes) in a wireless communication system are powered by batteries and it is desirable for such devices to have a predictable, extended battery life. A predictable battery life allows system operators to coordinate battery replacement maintenance for a group of nodes. An extended battery life enables less frequent battery replacement.